Theologian John Piper has weighed in on the "change is possible" debate, arguing that the possibility of changing one's sexual orientation should not be ruled out.

But the Reformed pastor also argued that sexual identity is complicated and cannot be simplified into three groups: heterosexual, homosexual and bisexual.

"There are hundreds of variations of impulses that make up our peculiar sexual identities. This means that 'change' is not a movement from one of three groups to another of three groups," Piper blogged on the Desiring God ministries website.

While the debate over whether gay persons can become straight has long been held, it gained the spotlight in May when Robert Spitzer, a retired professor of psychiatry, recanted a study he did a decade ago. In that study, he concluded that reparative therapy could change a patient's sexual orientation.

"I believe I owe the gay community an apology for my study making unproven claims of the efficacy of reparative therapy. I also apologize to any gay person who wasted time and energy undergoing some form of reparative therapy because they believed that I had proven that reparative therapy works with some 'highly motivated' individuals," Spitzer wrote in a letter to the editor of Journal of Sexual Behavior, which had published his previous study.

Though Spitzer has retracted his study, Piper, who serves as pastor for Preaching and Vision at Bethlehem Baptist Church in Minneapolis, noted that there are other psychologists who are sticking to their conclusions that change is possible.

"We should follow Stanton Jones and Mark Yarhouse in refusing to reject the possibility of change," said Piper. "Jones and Yarhouse do not recant their 2011 study in the Journal of Sex and Marital Therapy titled, 'A Longitudinal Study of Attempted Religiously Mediated Sexual Orientation Change.'"

In that study, they wrote that some people experience "meaningful shifts in sexual orientation" and that they don't believe "reports of change can be summarily dismissed."

"Much of the science surrounding sexual orientation in general and efforts to change sexual orientation in particular is yet inconclusive. Some may be able to change their sexual orientation to a degree, but many, perhaps the majority, cannot and will not. People may be harmed when practitioners, professional or religious, do not properly protect human welfare, but harm does not appear inevitable."

Piper, who argues that the Bible is "not unclear that same-sex attraction is disordered and that same-sex intercourse is sin," commended Jones and Yarhouse for their "wise and cautious balance."

"It is wise not only because with God all things are possible, but also because 'either-or' thinking is especially unsuitable when dealing with sexual orientation," Piper stated.

Given that sexuality cannot be boiled down simply to three groups, "change," he said, "is a totally unpredictable reconfiguration of dozens of impulses and desires."

"And these desires and impulses are interwoven with dozens of personal and relational and spiritual realities, all of which are moving and shifting as God and his word and his people come to bear on the totality of a person's life."

"From this perspective change is inevitable. We are all changing - in a hundred ways including how sexuality fits into our lives," he added.

"Whether sexual orientation can change or not, hearts can change and turn any sexual orientation into an occasion for the glory of Christ," said Piper. "Those with same-sex attraction glorify Christ through sexual abstinence and through the enrichment of significant Christ-exalting relationships in other ways."